Re: [Bier] Comments on draft-chen-bier-frr-02.

Huaimo Chen <huaimo.chen@futurewei.com> Wed, 17 March 2021 19:14 UTC

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From: Huaimo Chen <huaimo.chen@futurewei.com>
To: Tony Przygienda <tonysietf@gmail.com>, "Jeffrey (Zhaohui) Zhang" <zzhang=40juniper.net@dmarc.ietf.org>
CC: "bier@ietf.org" <bier@ietf.org>
Thread-Topic: [Bier] Comments on draft-chen-bier-frr-02.
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Date: Wed, 17 Mar 2021 19:14:09 +0000
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Archived-At: <https://mailarchive.ietf.org/arch/msg/bier/n1F2woi5Gtvi2XpEYKHKLH0SUks>
Subject: Re: [Bier] Comments on draft-chen-bier-frr-02.
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Hi Tony,

    Thanks much for your comments.
    My responses are inline below with [HC].

Best Regards,
Huaimo
________________________________
From: Tony Przygienda <tonysietf@gmail.com>
Sent: Wednesday, March 17, 2021 12:47 PM
To: Jeffrey (Zhaohui) Zhang <zzhang=40juniper.net@dmarc.ietf.org>
Cc: Huaimo Chen <huaimo.chen@futurewei.com>om>; bier@ietf.org <bier@ietf.org>
Subject: Re: [Bier] Comments on draft-chen-bier-frr-02.






In my view, the following does handle multiple failures to maximum extent:

zzh> A better way is to simply have a single BIFT for both normal and FRR
forwarding. Each entry has some ECMP and/or primary/backup branches,
and you simply use another ECMP branch or a backup branch when the
normally used branch fails. A backup branch can go through completely
different nbr, or go through the same neighbor but via a tunnel.


Consider that and the cost associated with building/maintaining multiple BIFTs, I would argue that the multiple per-nbr FRR BIFT approach, while perhaps acceptable for a particular implementation, is not ready yet for WG adoption.



Please note that I am not arguing against LFA based FRR. I am just saying that the reference model of a single BIFT with ECMP/primary/backup branches for an entry is the best baseline.

as participant and from experience

+10

in that sense merling's paper seems a better model to talk about stuff. Plus the technical concerns about the compressed multiple BIFTs on multiple failures

[HC]: The starting point of the draft is the LFA-based BIER FRR.
The compression is optional. Regarding to multiple BIFTs or a single BIFT,
we can include a single BIFT in the draft for comparisons.
Since the draft is experimental, we can choose one after
some experiments and/or research on them.

-- tony